File exists when confirmed in script but not when open is attempted by same script

greymoose has asked for the wisdom of the Perl Monks concerning the following question:

I have a cgi-script that is supposed to run another script via system and then open a txt file to read two lines of data. All is fine until it tries to open the file. In both terminal and browser I get the error message 'No such file or directory.' No amount of googling or searching the archives in the Monastery has helped me. As far as I can tell the file is valid because:

I have checked the file's existence and permissions manually in the file system and using -e, -w and -r in the script.
The file in question is opened by the second script that is called. (I get the same message when the second script is not called so I am confident it relates to the attempt to open the file for reading in this script.)

The script follows including the test for the file which is really only for troubleshooting:

#!/usr/bin/perl -w
use lib "/usr/local/lib/perl/lib/perl5/site_perl/5.8.8";
use CGI qw(:standard);
use CGI::Carp qw(warningsToBrowser fatalsToBrowser);
use strict;
print header;
    my ($x, $y);
    my $datafile = "/full/path/to/file/data.txt";
    system("perl /full/path/to/file.cgi")==0 or die "system failed $?"
+;    
if(!(-w $datafile)){
    print "What file?<br>";
}    
else{    
    open (FILE, '<', '$datafile') || die "Could not read $datafile $!\
+n";
        $x = <FILE>;        
        $y = <FILE>;
    close (FILE);
}
print $x."<br>";
print $y."<br>";
[download]

I'd appreciate any thoughts on why the same script is getting different results in relation to exactly the same file.

Comment on File exists when confirmed in script but not when open is attempted by same script Download Code

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Re: File exists when confirmed in script but not when open is attempted by same script by ikegami (Patriarch) on Jun 12, 2009 at 02:23 UTC
You check if the file named by the value of `$datafile` is writable, then you try to open the file named `$datafile` which doesn't exist. Get rid of those quotes! By the way, if you declared `$x` and `$y` where you actually gave them a value, you wouldn't be trying to print out variables you haven't initialized. `#!/usr/bin/perl -w use strict; use warnings; use lib "/usr/local/lib/perl/lib/perl5/site_perl/5.8.8"; use CGI::Carp qw(warningsToBrowser fatalsToBrowser); use CGI qw(:standard); print header; my $datafile = "/full/path/to/file/data.txt"; system('perl', '/full/path/to/file.cgi')==0 or die "system failed $?/$!"; open(my $fh, '<', $datafile) or die "Can't open file $datafile: $!\n"; chomp( my $x = <$fh> ); chomp( my $y = <$fh> ); print "$x<br>\n"; print "$y<br>\n";` [download]	[reply] [d/l] [select]
Re^2: File exists when confirmed in script but not when open is attempted by same script by greymoose (Beadle) on Jun 12, 2009 at 03:29 UTC
Doh! I thought it would be something stupid. Thanks for the help. Point taken about printing the uninitialized variables, too. The file is checked in the called script so it won't be in this one when it is complete, as a result the problem will cease to exist. Nonetheless I obviously need to be more observant. Thanks for the pointer.	[reply]